JPH09190815A - Method for producing lithium nickelate positive electrode plate and lithium battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high performance of nickel-acid lithium positive electrode plate which is improved in contact condition of a collector and an active material, by holding nickel hydroxide to a conductive porous body, and then, impregnating lithium nitrate solution, and after that, applying a heat treatment. SOLUTION: To a porous body having a conductivity as a collector, such as a porous body of nickel, carbon, aluminum, or stainless steel nickel hydroxide is held, and then, lithium nitrate solution is impregnated, or lithium nitrate is filled, and after that, a heat treatment is applied to manufacture a nickel-acid lithium positive electrode plate. Since an active material is filled in the condition the current collecting structure is formed solidly, the contacting condition of the collector and the active material, or between the active materials each other, is improved, and the active material is charged and discharged evenly. Furthermore, by impregnating the lithium nitrate after oxidizing the nickel hydroxide into an oxy-nickel hydroxide beforehand, or by including cobalt to the nickel hydroxide, the performance of the positive electrode plate is improved.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a lithium-containing nickel oxide.

[0002]

2. Description of the Related Art In recent years, with the development of electronic equipment, the appearance of new high-performance batteries is expected.

Currently, manganese dioxide / zinc batteries are used as primary batteries for electronic equipment, and nickel-cadmium batteries, nickel-zinc batteries, nickel-based batteries such as nickel-hydride batteries and lead batteries are used as secondary batteries. It is used. An alkaline aqueous solution such as potassium hydroxide or an aqueous solution such as sulfuric acid is used as an electrolyte for these batteries.

Recently, in place of these aqueous solution type batteries, a battery using a non-aqueous electrolyte solution has been developed as a battery having a higher energy density, and a representative battery thereof is a negative electrode. There are lithium batteries that use lithium.

Primary batteries include manganese dioxide-lithium batteries and carbon fluoride-lithium batteries, and secondary batteries include manganese dioxide-lithium batteries and vanadium oxide-lithium batteries.

A secondary battery using metallic lithium for the negative electrode has a drawback that a short circuit is likely to occur due to dendrite deposition of metallic lithium and the life is short, and safety is ensured due to high reactivity of metallic lithium. Since it is difficult to do so, so-called lithium-ion batteries, which use graphite or carbon for the negative electrode and lithium cobalt oxide for the positive electrode, have been devised for high-capacity batteries,
It is used as a high energy-density battery.

However, since lithium cobalt oxide is expensive, a lithium-containing manganese composite oxide or lithium nickel oxide has been proposed as an alternative.

In the case of this lithium-containing manganese composite oxide, there is a problem that the theoretical capacity density is low and the capacity decreases greatly with charge / discharge cycles.

On the other hand, lithium nickel oxide (lithium-containing nickel oxide) has the same crystal structure as practically used lithium cobalt oxide, but Solid State Ionics, 44,
87,1990 and Chem.Express, 7,689,1992 or the 33rd Annual Meeting of the Battery Symposium, P.21 (1992), the structure is similar to the rock salt structure, and nickel and lithium. Since the ions are easily replaced and an asymmetric structure is generated, there is a problem that the capacity is reduced.

As a manufacturing method for solving this problem, for example, J. Electrochem. Soc., 140, 1862, 1993,
Ni (NO ₃ ) ₂ , Ni (O) as the basic material of nickel
H) ₂ and NiCO ₃ as lithium sources for LiOH,
Using LiNO ₃ and Li ₂ CO ₃ , 750 ° C.-9
A heat treatment of 00 ° C. is performed. Also, Chem.Express,
No. 7,689,1992, NiCO ₃ and LiNO ₃ are pressurized to form pellets, which are then heat-treated in an oxygen stream at 750 ° C. for synthesis. Eur.Patent No.0345707, USAPatent N
In o.4980080 (1989), a mixture of NiO and LiOH is heat-treated at 700 ° C. In addition, Solid St
Atate Ionics, 69, 238, 1994, 1994, Ni (OH) ₂ and LiOH are heat-treated at 650 ° C.

In addition to such means for improving the production conditions, attempts have been made to replace a part of nickel with other elements in order to stabilize lithium nickelate. For example, in Solid State Ionics, 57, 311, 1992, manganese is substituted. Also, Chem.Express, 6,161,199
In 1, the cobalt was substituted, and the production method was Ni (NO ₃ ) ₂ , CoNi (NO ₃ ) ₂ and Li.
After mixing an aqueous solution of OH, predrying at 90 ° C, and then heat-treating at 800 ° C in air, lithium cobalt nickelate LiNi _1-X Co _X O ₂ (0 ≦ Co ≦ 0.5)
Is getting Also, Solid State Ionics, 53-56,370,199
In No. ₂ , Li ₂ CO ₃ , NiO and Co ₃ O ₄ are heat-treated at 800 ° C. to 1000 ° C. in an oxygen atmosphere.

Further, there have been attempts to utilize nickel oxyhydroxide, and in JP-A-63-19760, nickel oxyhydroxide containing 20 to 75% of cobalt is used as an active material for a lithium battery. 63-19761 proposes to use nickel hydroxide charged in a lithium hydroxide solution as an active material.

In addition, JP-A-6-31045 proposes that a hydroxide or oxide containing trivalent nickel ions is mixed with a lithium salt and then heat treated in order to improve discharge characteristics. doing. According to this, nickel oxyhydroxide prepared by reacting a sodium hydroxide solution in which divalent nickel hydroxide (Ni (OH) ₂ ) is dispersed with an aqueous solution of sodium hypochlorite, an aqueous solution containing chlorine or an aqueous solution containing bromine is prepared. After mixing the hydroxide or oxide containing it with lithium nitrate, pressurizing, molding and drying it at 600 ℃ -80
After heating in 0 ° C air, crushing and molding again to 700 ° C-90
Lithium nickelate is manufactured by heating and sintering in air at 0 ° C.

However, in addition to the difficulty in producing a pure lithium nickel oxide, the voltage of the charge / discharge characteristics changes in multiple steps, for example, in four steps, and also high rate discharge performance is obtained. There is a major drawback of decreasing.

Recently, as proposed in Japanese Patent Application No. 7-129663, nickel nickel oxyhydroxide containing cobalt is reacted with lithium nitrate to form lithium nickel oxide showing a uniform charge / discharge reaction. Although there is an attempt to synthesize it, even if an active material produced by any of these methods is used, in order to obtain a lithium nickelate positive electrode plate, the active material is pulverized into fine particles, and then carbon etc. of a conductive material is used. And a binder such as polyvinylidene fluoride and a metal collector, for example, a collector of aluminum or nickel, is applied.

Therefore, there is a problem that the manufacturing process is complicated and the performance is greatly influenced by the amounts of the carbon powder and the binder.

Therefore, there is a demand for a method of synthesizing an active material having more stable performance and a method of manufacturing which can simplify the electrode plate manufacturing process.

[0018]

As described above, it is difficult to produce a pure lithium nickel oxide, and the voltage of the charge / discharge characteristics is changed in multiple stages, and further, the high rate discharge performance is also high. Since it has a big defect that it is deteriorated, it has not reached the substitute of lithium cobalt oxide having the same layered structure.

From the viewpoint of the electrode reaction, it is considered that lithium nickelate is difficult because the diffusion of lithium ions accompanying the charge / discharge reaction is difficult and the diffusion is not uniform.

In addition, it is considered that one of the causes is that a method for synthesizing a lithium nickel oxide having a uniform structure or one having a large surface area or an optimum electrode structure between the active material and the current collector has not been established.

Therefore, the present invention was made in order to solve the above problems, and the object thereof is that the current collector and the active material or the active materials are in good contact with each other, and the electrode reaction does not occur. It is an object of the present invention to provide a manufacturing method capable of uniformly producing a high-performance lithium nickelate positive electrode plate.

It is another object of the present invention to provide an economically excellent method for producing a lithium nickelate positive electrode plate, which does not require complicated steps in the electrode plate manufacturing process.

[0023]

The first aspect of the present invention is to provide a method for producing a lithium nickelate positive electrode plate in which nickel hydroxide is impregnated with nickel hydroxide held in a conductive porous body. And heat treatment.

A second invention according to the first invention is characterized in that nickel oxyhydroxide is held in a porous body having conductivity.

A third invention according to the second invention is characterized in that the electroconductive porous material holding nickel hydroxide is electrochemically oxidized to form nickel oxyhydroxide.

A fourth invention according to the first, second or third invention is characterized in that the conductive porous body is made to hold nickel hydroxide and lithium nitrate and then heat treated.

A fifth invention according to the first, second, third or fourth invention is characterized in that nickel hydroxide or nickel oxyhydroxide contains cobalt.

The sixth invention according to the first, second, third, fourth and fifth inventions is characterized in that the material of the conductive porous body is nickel, carbon, aluminum or stainless steel.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is not a conventional method for producing an active material of lithium nickel oxide, but a conductive porous body which is a current collector, for example, a porous body of nickel, carbon, aluminum or stainless steel. A method for producing a lithium nickelate positive electrode plate, which comprises holding nickel hydroxide, impregnating it with a lithium nitrate solution, filling it with lithium nitrate, and then heat treating it.

As a result, the active material is filled in the state where the current collecting structure is firmly formed, so that the contact state between the current collector and the active material or the active material is good, and the active material is uniformly charged and discharged. As a result, the charge / discharge characteristics and charge / discharge cycle performance are improved.

Further, since the active material can be directly filled on the surface and inside of the current collector, first, as in the conventional manufacturing method, the active material powder is first produced by synthesis,
The active material powder and acetylene black powder or the like as a conductive material, and polyvinylidene fluoride or the like as a binder are dissolved in
-Methyl-2-pyrrolidene and other solutions are mixed in a dry room to form a paste, which is then applied to the nickel or aluminum sheet of the current collector, and then the complex process of drying is not required, which is economical. It is an excellent method for producing a lithium nickelate positive electrode plate.

Further, if nickel hydroxide is previously oxidized to nickel oxyhydroxide and then impregnated with lithium nitrate or cobalt is contained in nickel hydroxide, the performance is improved.

In addition, when nickel oxyhydroxide (Ni _1-X Co _X OOH) containing cobalt and having an average valence of 3 or more is used as a raw material, an atmosphere containing a small amount of oxygen can be obtained. , Lithium nickel oxide can be efficiently synthesized.

Therefore, the positive electrode plate obtained by the production method according to the present invention has extremely useful characteristics which have not been reported in the electrochemical characteristics. That is, the positive electrode plate of the present invention is excellent in high-rate discharge performance of 1 C or more and has a continuous curve of charge / discharge characteristics.

The lithium nitrate solution is preferably a melt.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail.

[Example 1] Carbonyl nickel powder used as an active material holder for a sintered nickel-cadmium battery was sintered to obtain a sintered nickel substrate (100 mesh) having a porosity of about 85%. Nickel mesh as the core material), as a method for producing a nickel hydroxide positive electrode plate for a battery,
A widely-used so-called vacuum impregnation method was applied to manufacture a substrate containing nickel hydroxide.

That is, 5 mol% [{Co / (Ni + Co)} ×
100] cobalt-containing 4M nickel nitrate aqueous solution was impregnated under reduced pressure at 5 mmHg, then neutralized in 5M sodium hydroxide aqueous solution and washed with hot water. Then, the conventionally known operation of drying at 100 ° C. is repeated 3 times,
An electrode plate filled with nickel hydroxide was manufactured.

Then, it was dipped in a 0.1 M sodium hydroxide aqueous solution, and two nickel plates were used as counter electrodes.
Anode current is applied for 3 hours at a current density of mA / cm ₂ ,
Nickel hydroxide was used as nickel oxyhydroxide.

After that, it is immersed in a molten solution of lithium nitrate kept at 350 ° C. and further heat-treated in air at 400 ° C. for 1 hour to react nickel hydroxide with lithium nitrate, and according to the present invention. A positive electrode plate A having a size of 30 mm × 40 mm × 0.8 mm and a nominal capacity of 200 mAh was manufactured.

Example 2 A sintering type nickel substrate having a porosity of about 85% obtained by sintering carbonyl nickel powder (a nickel mesh of 100 mesh is used as a core material) and 5 mo
A 4 M nickel nitrate aqueous solution containing 1% [{Co / (Ni + Co)} × 100] cobalt is impregnated under reduced pressure at 5 mmHg, then neutralized in a 5 M aqueous sodium hydroxide solution and washed with hot water. Then, a conventionally known operation of drying at 100 ° C. was repeated 3 times to manufacture a polar plate filled with nickel hydroxide.

Subsequently, the nickel hydroxide was made nickel oxyhydroxide by immersing it in a 0.1 M sodium hydroxide aqueous solution in which potassium peroxosulfate was dissolved.

Then, after immersing in a molten liquid of lithium nitrate kept at 350 ° C., it is further heated in air to 400
A positive electrode plate B according to the present invention having a size of 30 mm × 40 mm × 0.8 mm and a nominal capacity of 200 mAh was produced by reacting nickel hydroxide with lithium nitrate by heating at 3 ° C. for 3 hours.

Example 3 A sintering type nickel substrate having a porosity of about 85% obtained by sintering carbonyl nickel powder (a nickel mesh of 100 mesh was used as a core material) was coated with 5 mol.
1% [{Co / (Ni + Co)} × 100] cobalt-containing 4M nickel nitrate aqueous solution was impregnated under reduced pressure at 5 mmHg, then neutralized in 5M sodium hydroxide aqueous solution and washed with hot water, The previously known operation of drying at 100 ° C.
Repeatedly, the electrode plate filled with nickel hydroxide was manufactured.

Next, it is dipped in a molten solution of lithium nitrate kept at 350 ° C. and further heat-treated in air at 400 ° C. for 3 hours to react nickel hydroxide with lithium nitrate, and the size is changed. 30mm × 40mm × 0.8mm with a nominal capacity of 200m
A positive electrode plate C according to the present invention of Ah was manufactured.

Example 3 Using foamed nickel having a porosity of 98% (trade name Celmet manufactured by Sumitomo Electric Industries, Ltd.), 100 parts of an aqueous solution of 0.1 wt% of carboxymethyl cellulose and 5 mol% [{Co / ( Ni + Co)} × 100] cobalt-containing 20 parts of 20 μm nickel oxyhydroxide powder mixed paste was filled and dried at 100 ° C. to prepare a nickel oxyhydroxide filled electrode plate.

Next, by immersing in a molten solution of lithium nitrate kept at 350 ° C., and further heat-treating in air at 400 ° C. for 1 hour to react nickel oxyhydroxide with lithium nitrate, and to carry out the present invention. Size is 30mm × 40mm × 0.8m
A positive electrode plate D according to the present invention having m 2 and a nominal capacity of 200 mAh was manufactured.

[Example 3] Foamed nickel having a porosity of 98% (trade name Celmet manufactured by Sumitomo Electric Industries, Ltd.) was used, and a 1 wt% aqueous solution of carboxymethyl cellulose 1
5 ml and 5 mol% [{Co / (Ni + Co)} × 100] of cobalt containing 20 μm of 20 μm nickel oxyhydroxide powder and 15 parts of a mixed paste of lithium nitrate powder were filled and dried at 100 ° C. . Then 400 in air
Heat treatment at 1 ° C for 1 hour to react nickel oxyhydroxide with lithium nitrate to give a size of 30 mm according to the present invention.
A positive electrode plate E according to the present invention having a size of × 40 mm × 0.8 mm and a nominal capacity of 200 mAh was manufactured.

As a comparative example, the conventional method, that is, 5 mo
Lithium nickelate heat-treated at 450 ° C. for 10 hours in an air atmosphere after mixing nickel oxyhydroxide powder containing 1% [{Co / (Ni + Co)} × 100] of cobalt and lithium nitrate powder in an equivalent amount. To produce an active material, and then mix it with a solution of n-methyl-2-pyrrolidene containing 1% of polyvinylidene fluoride to obtain nickel foam having a porosity of 98% (a product manufactured by Sumitomo Electric Industries, Ltd. Name Celmet)
After filling it in, it is dried at 100 ℃ and the size is 30mm × 40
A positive electrode plate F having a nominal capacity of 200 mAh with a size of 0.8 mm was manufactured.

Using two metal lithium plates having the same size as one of these positive electrode plates and 300 ml of a mixed solution of ethylene carbonate and diethyl carbonate containing 1M lithium perchlorate as an electrolytic solution, a test battery was prepared. I made it. A metal lithium reference electrode was used to measure the potential of the positive electrode.

This battery is 4.3 V at 20 ° C. and 20 mA.
FIG. 1 shows the discharge characteristics when the battery was charged to (metal lithium) and then discharged at 200 mA.

From the figure, the positive electrode plates A, B, C according to the present invention,
The discharge performances of D and E clearly show that the conventional positive electrode plate F
It turns out that it is superior to the case of.

FIG. 2 shows the change in discharge capacity with the increase in the number of cycles when charging and discharging under the same conditions.

From the figure, the positive electrode plates A, B, C according to the present invention,
It can be seen that the discharge capacities of D and E are good, as compared with the case of the conventional positive electrode plate F, with less decrease in capacity with increase in the number of charge / discharge cycles.

In each example, nickel hydroxide or nickel oxyhydroxide was used as the nickel source of lithium nickelate. It was confirmed that the performance was further improved by using nickel.

Co / (Ni of the nickel nitrate used in Example 1
The positive electrode plates manufactured by changing the + Co) molar concentration were charged and discharged under the same conditions as in FIG. 1, and the discharge capacity obtained at the 50th cycle was divided by the discharge capacity at the first cycle to obtain the value. The relationship between the capacity retention rate and the cobalt content rate was obtained.
This is shown in FIG.

From the figure, it is understood that the capacity retention becomes particularly good when the cobalt content is 2 mol% or more. As described above, when cobalt is contained, the capacity retention is improved because the diffusion of lithium ions of lithium nickel oxide containing cobalt becomes easier, and it is presumed that the active material acts uniformly, and as a result, It is conceivable that the deterioration will decrease.

As described above, the reason why the positive electrode plate of the present invention has excellent performance is that the active material of the positive electrode plate of the present invention is a porous body of nickel or the like having both an active material holder and a current collector. Since the active material and the current collector are directly contacted with each other by being synthesized and retained, the particles of the nickel oxide nickel oxide particles, which are active materials, are well bonded to each other. It is presumed that the contact resistance between the particles is small, and that diffusion of lithium ions, which is the process of controlling the reaction, is facilitated between the particles.

In addition, although nickel was used as the material of the active material holding substrate in the example, the same effect can be obtained with stainless steel. However, when aluminum or carbon is used as the material, a heat treatment in an atmosphere containing oxygen easily forms a thick oxide film layer on the surface, which lowers the mechanical strength of the electrode plate and also reduces the conductivity. In some cases, after the nickel oxyhydroxide is filled, the heat treatment may be performed in an environment where the oxygen content is smaller than that in the air atmosphere and at a low temperature of 350 ° C. or lower.

As nickel oxyhydroxide, β type, γ type
Although it may be in the form or a mixture thereof, nickel oxyhydroxide has a low content of γ-NiOOH, and is preferably free of water of crystallization, especially in the case of aluminum, which also forms a hydroxide with water. β-NiOOH is good.

Even when nickel is used as the material, if the heat treatment temperature exceeds 410 ° C. in an air atmosphere, an oxide film on the surface of the nickel substrate is thickly formed. Therefore, the heat treatment temperature is preferably 400 ° C. or lower. preferable.

In order to suppress the formation of such an oxide film, it is possible to suppress the corrosion at the time of impregnation of a nickel substrate of sintered nickel-cadmium as reported in Japanese Patent Publication No. 55-64372. Therefore, when the technique of forming a thin and uniform oxide film of nickel on the surface of the nickel base material by heat treatment in an atmosphere containing air or oxygen is applied to the present invention, nickel by heat treatment in an oxygen-containing atmosphere is applied. It could be confirmed that the strength of the substrate was reduced, or the effect of suppressing oxidation of the substrate due to decomposition of lithium nitrate was suppressed.

The performance of the positive electrode plate according to the present invention has been described above in the case of a non-aqueous solution battery. The positive electrode plate according to the present invention uses an aqueous solution battery, for example, an electrolytic solution containing lithium ions such as an aqueous solution of lithium nitrate. It can be applied to both primary batteries and secondary batteries. In that case, nickel is desirable as the material of the substrate.

[0064]

The first aspect of the present invention is a method for producing a lithium nickelate positive electrode plate, in which nickel hydroxide is held in a conductive porous body, and then a lithium nitrate solution is impregnated and heat treated. It is characterized by

A second invention according to the first invention is characterized in that nickel oxyhydroxide is held in a porous body having conductivity.

The third invention according to the second invention is characterized in that the conductive porous body holding nickel hydroxide is electrochemically oxidized to nickel oxyhydroxide.

A fourth invention according to the first, second or third invention is characterized in that the conductive porous body is made to hold nickel hydroxide and lithium nitrate and then heat treated.

The fifth invention according to the first, second, third or fourth invention is characterized in that nickel hydroxide or nickel oxyhydroxide contains cobalt.

The sixth invention according to the first, second, third, fourth and fifth inventions is characterized in that the material of the conductive porous body is nickel, carbon, aluminum or stainless steel.

According to the present invention, unlike the conventional lithium nickel oxide positive electrode plate, the method of synthesizing lithium nickel oxide once and then coating it on the current collector or filling the porous body thereof directly is used. Since the active material is synthesized and filled in the conductive base material, the active material and the current collector are electrically contacted well, and the lithium nickel oxide particles as the active material are well joined to each other. In addition, the contact resistance between particles is small, and the diffusion of lithium ions, which is the process of controlling the reaction, is facilitated even between particles, so that a very high-performance positive electrode plate can be obtained and provided.

Further, since the manufacturing process of the electrode plate can be simplified as compared with the conventional electrode plate manufacturing process, it is possible to provide an economically excellent and inexpensive positive electrode plate.

[Brief description of the drawings]

FIG. 1 is a diagram showing discharge characteristics of a positive electrode plate according to the present invention and a conventional positive electrode plate.

FIG. 2 is a diagram showing the relationship between the number of charge / discharge cycles and the discharge capacity of a positive electrode plate according to the present invention and a conventional positive electrode plate.

FIG. 3 is a diagram showing the relationship between the capacity retention rate and the cobalt content rate at the 50th cycle when the positive electrode plate is charged and discharged.

[Explanation of symbols]

Claims (7)

[Claims] 1. A method for producing a lithium nickelate positive electrode plate, which comprises holding nickel hydroxide in a porous body having conductivity, impregnating it with a lithium nitrate solution, and heat-treating it. 2. The method for producing a lithium nickelate positive electrode plate according to claim 1, wherein nickel oxyhydroxide is held in a conductive porous body. 3. The method for producing a lithium nickelate positive electrode plate according to claim 2, wherein the conductive porous body holding nickel hydroxide is electrochemically oxidized to form nickel oxyhydroxide. 4. A method for producing a lithium nickelate positive electrode plate, which comprises holding nickel hydroxide and lithium nitrate in a conductive porous body and then heat treating the same. 5. The nickel hydroxide or nickel oxyhydroxide containing cobalt.
The method for producing a positive electrode plate of lithium nickel oxide according to 2, 3, or 4. 6. The material of the conductive porous body is nickel, carbon,
The method for manufacturing a lithium nickelate positive electrode plate according to claim 1, wherein aluminum or stainless steel is used. 7. A lithium battery comprising a positive electrode plate manufactured by the manufacturing method according to claim 1, 2, 3, 4, 5 or 6.